Phosphorous-containing catalyst and method for preparing and using same

ABSTRACT

An improved method for preparing a hydrocarbon hydrotreating catalyst containing a major amount of alumina and a minor amount of at least one Group VIB or Group VIII metal comprising: 
     (1) contacting an aqueous mixture of hydrous alumina with at least one phosphorus-containing compound in an amount sufficient to increase the hydrocarbon hydrotreating activity of the final catalyst and forming a phosphorus-containing hydrous alumina; 
     (2) calcining the phosphorus-containing hydrous alumina and forming a calcined alumina; 
     (3) contacting the calcined alumina with at least one metal-containing compound and forming a metal-containing material, the metal being selected from the group consisting of Group VIB metal, Group VIII metal and mixtures thereof; and 
     (4) calcining the metal-containing material and forming a catalyst having increased hydrocarbon hydrotreating activity. 
     Improved hydrocarbon hydrotreating processes and catalysts are also disclosed.

This is a continuation of application Ser. No. 559,983, filed Mar. 19,1975, now abandoned, which is a continuation of Ser. No. 369,265, filedJune 12, 1973, now abandoned.

The present invention relates to improved hydrocarbon hydroconversioncatalysts and methods for preparing and using same. More particularly,the present invention relates to improved hydrocarbon hydrotreatingcatalysts comprising alumina, phosphorus and at least one catalyticmetal, and improved methods for making and using same.

Hydrocarbon hydrotreating has become increasingly more important becauseof the demand for high quality hydrocarbon feedstocks and products,e.g., materials with reduced sulfur and/or nitrogen contents. Broadly,hydrocarbon hydrotreating refers to a process wherein a hydrocarbonmaterial containing an undesirable contaminant, e.g., sulfur, nitrogenand the like, is contacted with a catalyst in the presence of hydrogenat conditions to form compounds of the undesirable contaminants whichcan be removed from the hydrocarbon material by conventional means,e.g., simple distillation and the like. In many instances, the catalystused comprises alumina and at least one metal in an amount effective topromote the hydrocarbon hydrotreating. In order to increase hydrocarbonhydrotreating process efficiency, it would be advantageous to provide acatalyst having improved properties, e.g., improved hydrocarbonhydrotreating activity.

Therefore, one of the objects of the present invention is to provide animproved hydrocarbon hydrotreating catalyst.

An additional object of the present invention is to provide an improvedmethod for producing a catalyst having improved hydrocarbonhydrotreating activity.

A further object of the present invention is to provide an improvedhydrocarbon hydrotreating process. Other objects and advantages of thepresent invention will become apparent hereinafter.

An improved method for preparing a hydrocarbon hydrotreating catalystcomprising a major amount of alumina and a minor amount of at least onemetal selected from the group consisting of Group VIB metal, Group VIIImetal and mixtures thereof has now been discovered. The improved methodcomprises:

(1) contacting an aqueous mixture of hydrous alumina with at least onephosphorus-containing compound including at least one acidic hydrogenatom, i.e., phosphorus acids, in an amount sufficient to increase thehydrocarbon hydrotreating activity of the final catalyst, hereinafterdescribed, and forming a phosphorus-containing hydrous alumina;

(2) calcining the phosphorus-containing hydrous alumina and forming acalcined alumina;

(3) contacting the calcined alumina with at least one metal-containingcompound and forming a metal-containing material, the metal beingselected from the group consisting of Group VIB metal, Group VIII metaland mixtures thereof, and being present in the metal-containing materialin an amount so that the final catalyst formed therefrom comprises acatalytically effective amount of the metal; and

(4) calcining the metal-containing material and forming a final catalysthaving increased hydrocarbon hydrotreating.

Thus, the above method has been found to provide a new and improvedcomposition of matter. The phosphorus-containing compound interacts withthe hydrous alumina in an as yet undetermined fashion to promote thehydrocarbon hydrotreating activity of the final catalyst suprisinglywithout substantially adversely affecting the other properties, e.g.,surface area, pore volume and the like, of the final catalyst.

The aqueous mixture contacted in step 1 of the above method preferablycomprises from about 5% to about 70%, more preferably from about 30% toabout 70% by weight, of hydrous alumina (calculated as Al₂ O₃). Thehydrous alumina used may be prepared by various methods known in theart. Thus, for instance, hydrated alumina can be precipitated from anaqueous solution of a soluble aluminum salt such as aluminum chloride.Ammonium hydroxide is a useful agent for effecting the precipitation.Control of the pH to maintain it within the values of about 4 to about10 during the precipitation is desirable for obtaining a good rate ofconversion. Extraneous ions, such as halide ions, which are introducedduring preparation of the hydrogel can, if desired, be removed byfiltering the alumina hydrogel from its mother liquor and washing thefilter cake with water. Also, if desired, the hydrogel can be aged, sayfor a period of several days, prior to utilizing it in the method of thepresent invention. The effect of such aging is to build up theconcentration of alumina trihydrates in the hydrogel. Such trihydrateformation can also be enhanced by seeding the slurries withcrystallites, of, for example, gibbsite. Thus, for instance, a majoramount, preferably from about 50 percent to about 95 percent, of thealumina content in the mixture of step (1) of the method can be in thetrihydrate form, e.g., as one or more of bayerite, gibbsite ornordstrandite (previously called randomite). Preferably, the hydrousalumina used in the mixture of step 1 predominates in a materialselected from the group consisting of alumina monohydrate, aluminatrihydrates, amorphous hydrous alumina and mixtures thereof. Morepreferably, this hydrous alumina predominates in a material selectedfrom the group consisting of alumina monohydrate, amorphous hydrousalumina and mixtures thereof, particularly, alumina monohydrate.

The hydrous alumina thus formed may be dried prior to being formed intoan aqueous mixture for contacting in step 1 of the present method. Thisdrying may be preferred in order to obtain a solid product which can bereadily comminuted and/or more easily handled and worked with. Thisdrying can be accomplished in various manners, for example, by drumdrying, flash drying, spray drying, tunnel drying and the like, withspray drying being preferred. The drying temperature of the hydrousalumina should be kept below the point at which substantial amounts ofwater of hydration, i.e., combined water, are released from the alumina.Usually, this drying will be carried out at temperatures below about500° F.

In any event, an aqueous mixture comprising the hydrous alumina iscontacted with at least one phosphorus acid. It is not critical to thepresent invention in what order the components are combined in step 1.For example, water containing the phosphorus acid can be combined withdried hydrous alumina; the phosphorus acid or a concentrated mixture ofwater and phosphorus acid can be combined with an aqueous mixture ofhydrous alumina; or the phosphorus acid, water and hydrous alumina fromseparate sources can be combined for the contacting of step 1. Thecontacting of step (1) may occur in a batch system, semi-batch system ora continuous system.

This contacting takes place under conditions sufficient to increase thehydrocarbon hydrotreating activity of the final catalyst. Although thecontacting conditions are not critical to the present invention, it ispreferred that the contacting take place at a temperature in the rangefrom about 35° F. to about 210° F., or more, more preferably in therange from about 50° F. to about 150° F. Contacting times in the rangefrom about 1 minute or less to about 20 hours or more may be used, withtimes in the range from about 1 minute to about 1 hour being preferred.The contacting of step 1 preferably takes place at conditions, e.g.,temperature and pressures, such that a substantial loss, e.g., greaterthan 30%, of the free water in the aqueous mixture by vaporization isavoided. Thus, for example, the contacting of step (1) may be carriedout at pressures in the range from about 1 atmosphere to about 10atmospheres or more.

The phosphorus acids used in the present invention are chosen to providea final catalyst having increased hydrocarbon hydrotreating activity.Preferably, the phosphorus acid is at least partially water soluble.Also included in the term phosphorus acids are phosphorus acidprecursors, that is phosphorus-containing compounds able to formcompounds containing at least one acidic hydrogen atom when in thepresence of water such as phosphorus oxides, phosphorus or halides andthe like. Included among the phosphorus acids useful in the presentinvention are ortho-, pyro-, meta-, hypo-phosphorous acids, phosphonicacids, phosphinic acids, phosphenic acids, phosphinic acids, phosphenicacids, phosphoranoic acids, phosphoranedioic acids, phosphoranetrioicacids, phosphorcinetetroic acids, phorphoranepentoic acids and mixturesthereof. Preferably, the phosphorus acids used is selected from thegroup consisting of phosphoric acid, phosphorous acids and mixturesthereof. Of course, mixtures of two or more phosphorus acids may beutilized. Substituted forms of the phosphorus acids also may be used.Suitable substitutents are chosen so as not to materially interfer withthe functions of the phosphorus acids in the present invention. Suchsubstituents include: halide, such as fluoride, chloride, bromide andthe like; NH₄ ; CN; monovalent essentially hydrocarbonaceous radicalscontaining from about 1 to about 30 or more carbon atoms and the like.Among the monovalent essentially hydrocarbonaceous radicals which may besubstituted on to the phosphorus acids are alkyl and alkenyl such asmethyl, ethenyl, butyl, butenyl, octyl, octenyl, hexyldecyl,hexyldecenyl and the like; aryl such as phenyl, naphthyl and the like;and alkaryl, alkenaryl, aralkyl and aralkenyl such as methyl-, butyl-and decyl-phenyl, ethenyl-butenyl-and decenyl-phenyl, benzyl, phenylbutyl, phenyl decyl, phenyl ethenyl, phenyl bitenyl, phenyl deconyl andthe like. Substituted monovalent hydrocarbonaceous radicals may be used,for example, to improve water solubility of the acid, provided that thesubstituent does not interfere with the functions of the phosphorusacids.

In a more preferred embodiment, the phosphorus acid used in step 1 isselected from the group consisting of phosphoric acids and mixturesthereof. The term phosphoric acids includes compounds which formphosphoric acids in the presence of water. It is preferred that thephosphorus acid be present in step 1 in an amount such that at leastabout 0.01 moles, more preferably from about 0.01 mole to about 2.0moles, more preferably from about 0.05 mole to about 1.0 moles, ofphosphorus is present per mole of alumina (calculated as Al₂ O₃).

The contacting of step 1 forms a phosphorus-containing hydrous aluminawhich can, if necessary, be dried in a manner similar to that describedpreviously for the hydrous alumina.

This phosphorus-containing hydrous alumina is to be calcined. However,prior to this calcination, it is preferred that this material be formedinto macrosized particles of a size suitable for use as a hydrocarbonhydrotreating catalyst. Forming the phosphorus-containing hydrousalumina into macrosize particles can be performed, for example, bytabletting, extruding and the like.

In the case of tabletting, it is preferred to incorporate in thephosphorus-containing hydrous alumina a minor amount of a die lubricantwhich is either substantially non-deleterious to the final catalyst orwhich can be removed by a subsequent calcining step. Often employed, forexample, are organic compounds, e.g., polyethylene, which, by calciningthe formed particles in an oxidizing atmosphere, can be subsequentlyburned away.

When macroforming by extrusion, sufficient water should be present inthe phosphorus-containing hydrous alumina to provide a workable dough.This can be accomplished by terminating the drying of thephosphorus-containing hydrous alumina once the free water content of thematerial has reached about 20 to about 60, preferably from about 20 toabout 40, weight percent. However, it may be preferred to first dry thephosphorus-containing hydrous alumina to obtain a material which is lowenough in water content to be readily comminuted, then, if necessary,comminute the material to a small particle size, add back water toachieve a dough-like consistency and then extrude thewater-phosphorus-containing hydrous alumina mixture into macrosizeparticles.

The size selected for the macrosize particles can be dependent upon theintended environment in which the final catalyst is to be used--as, forexample, whether in a fixed or moving bed reaction system. Thus, forexample, where, as in the preferred embodiment of the present invention,the final catalyst composition is designed for use as a catalyst inhydrocarbon hydrotreating operations employing a fixed bed of catalyst,the phosphorus-containing hydrous alumina will preferably be formed intoparticles having a minimum dimension of at least about 0.01 inch and amaximum dimension up to about one-half inch or one inch or more.Particles having a diameter of about 0.03 inch to about 0.25 inch,preferably about 0.03 inch to about 0.15 inch, are often preferred,especially for use in fixed bed hydrotreating operations.

Calcining of the phosphorus-containing hydrous alumina, e.g., in theform of macroformed particles, according to step (2) of the method isperformed at temperatures sufficient to effect release of the water ofhydration of the phosphorus-containing hydrous alumina. Generallysuitable are temperatures in the range from about 600° F. to about 1200°F., preferably from about 850° F. to 1000° F. This calcination takesplace preferably over a period of time of at least about 1/2 hour, morepreferably over a period of time in the range from about 1 hour to about6 hours. The calcination can be effected in an inert atmosphere such asnitrogen, as well as in either an oxidizing or reducing environment.Thus, either oxygen-containing gases, such as dry air, orhydrogen-containing gases may be advantageously employed. Inert diluentgases such as nitrogen can be present in admixture with the oxygen orhydrogen. It is usually advantageous to conduct the calcination in aflowing stream of the gaseous atmosphere. Atmospheric, super-atmosphericor sub-atmospheric pressures can be employed.

Where the phosphorus-containing hydrous alumina, e.g., in the form ofmacrosize particles, contains significant amounts, say about 5 weightpercent or more, of uncombined water--as, for example, will usually bethe case where the macroformed particles have been formed byextrusion--then, either as a separate operation or in the first stage ofthe calcination, the phosphorus-containing hydrous alumina can, withadvantage, first be dried at a temperature below the point at whichsubstantial amounts of combined water are released from the alumina.Higher temperatures can cause fissures and rupture of the macroformedparticles. Thus, prior to being heated to as high as about 700° F.,preferably prior to being heated above about 500° F., the uncombinedwater content of the phosphorus-containing hydrous alumina should belowered to at least below about 5 weight percent.

The calcining of step (2) of the present invention forms calcinedalumina, e.g., in the form of macrosized particles. The calcined aluminais contacted with at least one metal-containing compound to form ametal-containing material which includes an amount of such metal so thatthe final catalyst formed therefrom comprises a catalytically effectiveamount of the metal. The metal-containing compound used comprises GroupVIB metals, such as chromium, molybdenum and tungsten, and/or the GroupVIII iron-group and platinum group metals, e.g., iron, cobalt, nickel,platinum, iridium, osmium, palladium, rhodium and ruthenium, andmixtures thereof. The catalytic metals can be present in the finalcatalyst as the free metals or in combined form such as the oxides andsulfides. Preferably, the final catalyst contains catalyticallyeffective amounts of at least one Group VIB metal and at least one GroupVIII iron-group metal. Especially preferred catalysts contain nickelcobalt and mixtures thereof together with tungsten, molybdenum andmixtures thereof. The Group VIP metals are preferably present in amountsof from about 5% to about 40%, more preferably from about 10% to about30%, by weight of the total catalyst, calculated as the weight of theGroup VIB metal oxide. The Group VIII iron-group metals are preferablypresent in an amount of from about 2% to about 15%, more preferably fromabout 4% to about 10%, by weight of the total catalyst, calculated asthe weight of the free metal. When they are used, the Group VIIIplatinum group metals preferably are present in an amount from about0.01% to about 2%, more preferably from about 0.05% to about 1%, byweight of the total catalyst calculated as the metal. Metals and/ormetal compounds in addition to the platinum group metal such as rhenium,germanium, tin and the like, may be included in the final catalyst toimprove the properties of the composition.

The contacting of step (3) of the above method can be carried out as isknown in the art. The metal is preferably in solution as a compoundwhich is a precursor of the form, e.g., free metal, metal oxide or metalsulfide, desired in the final catalyst. For example, to prepare acatalyst containing nickel and molybdenum oxide (MoO₃), a solution ofnickel nitrate and ammonium molybdate in ammonia and water can be usedas the impregnating solution. The metal-containing material can then bedried, as, for example, at a temperature of about 100° C. to about 130°C. for a time such as 15 to 20 hours, and then calcined. Alternatively,ammonium molybdate can be dissolved in a solution of aqueous ammonia,prepared by admixing 29% ammonia and water in a ratio of 1.76:1, nickelnitrate is then added in this solution and forms the nickel aminecomplex (Ni(NH₃)₆ ++). This solution can then be used as the impregnantwith the metal-containing material being dried and calcined as before.After impregnation, the metal-containing material can be recalcined atthe conditions, e.g., temperatures, previously noted. The impregnationof the calcined alumina with the catalytic metal solutions can also beperformed sequentially, that is, for example, impregnation with asolution of ammonium molybdate in ammonia followed by drying andcalcination of the particles and then impregnation of the molybdenumoxide containing support with a solution of nickel nitrate followed byanother drying and calcination. Alternatively, the calcined alumina maybe impregnated with the Group VIII metal first.

In any event, the metal-containing material from step (3) is calcined,for example, at the conditions noted previously for the calcination instep (2) of the present method, to form a final catalyst.

The final catalyst of the present invention preferably contains at leastabout 0.5% by weight of phosphorus. More preferably, the phosphoruscontent is from about 1.0% to about 10.0% by weight of the finalcatalyst. This catalyst preferably has a surface area of at least about100 m²./gm., more preferably, at least about 150 m²./gm. The total porevolume of the final catalyst is preferably at least about 0.50 cc./gm.,more preferably at least about 0.70 cc./gm. Other characteristics ofthis catalyst which may contribute to its beneficial properties have notas yet been determined. However, the method of the present inventiondoes provide a unique and improved hydrocarbon hydrotreating catalyst.

The final catalyst can be reduced in hydrogen, as by heating thecatalyst in a stream of hydrogen at a temperature of from about 400° F.to about 1000° F., preferably from about 500° F. to about 800° F. Toconvert the metal and/or metal oxides in the catalyst to the sulfides,the final catalyst, containing the metals in oxide form as obtained fromthe calcination of step (4) may be sulfided by passing hydrogen sulfide,either pure or diluted with another gas, such as, for instance,hydrogen, over the catalyst bed at temperatures usually below about 800°F., preferably from about 400° F. to about 400° F., for a timesufficient to convert a significant portion of the oxides of the metalcomponents to their respective sulfides. Alternatively, the catalyst maybe sulfided during processing by the sulfur in the feed. Also, themetals can be deposited in the sulfide form during the manufacture ofthe final catalyst as noted above.

The final catalyst prepared as described above is particularly useful inthe hydrotreating of substantially hydrocarbon feedstocks such assulfur-containing and/or nitrogen containing mineral oil derived frompetroleum, coal, shale oil, tar sand oil and the like. Distillatefeedstocks including heavy oil distillates, having end boiling points upto about 1100° F., are especially preferred. Typical distillates whichmay be processed using the present catalyst include those having atleast about 0.5% by weight sulfur and or at least about 100 ppm.nitrogen and boiling primarily in the range from about 150° F. to about1050° F., or more, preferably in the range from about 250° F. to about550° F. The substantially hydrocarbon feedstock can be contacted withhydrogen over the final catalyst prepared as described above in at leastone reaction zone at conditions such as a temperature, for example, inthe range from about 650° F. to about 900° F., preferably from about700° F. to about 850° F., sufficient to form compounds of theundesirable components of the feedstock, e.g., sulfur and/or nitrogen,with hydrogen which can be removed by conventional processing, e.g.,flashing, simple distillation, vacuum distillation and the like. Othersuitable contacting conditions include pressures from about 300 psi. toabout 5000 psi., preferably from about 300 psi. to about 1500 psi.;weight hourly space velocities of from about 0.5 to about 4, preferablyabout 1 to about 3 and hydrogen flow rates of from about 300 to about30,000 standard cubic feet of hydrogen per barrel of feedstock,preferably from about 300 to about 5,000 standard cubic feet of hydrogenper barrel of feedstock. In many instances, contact of the feedstockover the final catalyst as set forth above allows the recovery of atleast one substantially hydrocarbon product having a sulfurconcentration and/or nitrogen concentration reduced from that of thefeedstock. This product recovery can be carried out using conventionaltechniques, e.g., flashing, distillation and the like, well known in theart.

EXAMPLE I

This example illustrates the improved method of the present invention.

982 grams of a hydrous alumina (igniyted weight 736 grams) comprising54.5% alumina monohydrate with the remainder being amorphous hydrousalumina was placed in a mechanically powered mixer. The mixer wasactivated. 1150 ml. of an aqueous solution containing 171.5 ml. of 85%by weight H₃ PO₄ was added to the mixer over a period of 10 minutes. Themixture of water, hydrous alumina and H₃ PO₄ was mulled at ambienttemperature, i.e., 72° to 75° F., and atmospheric pressure for anadditional 15 minutes. The resulting phosphorus-containing hydrousalumina was extruded through a 1/16 in. die plate using a double augerextruder. The extruder was dried for 20 hours at 230° F. in a forceddraft oven, broken into approximately 1/8 inch lengths and calcined inair in a muffle furnace programmed to raise the temperature 300° F./hr.to 900° F., hold 900° F. for 6 hours and cool. The product calcinedalumina was found to contain 5.95% by weight of phosphorus.

162 grams of this calcined alumina was vacuum impregnated withNi(NO₃)₂.6H₂ O and (NH₄)₆ MoO₇.4H₂ O, dried and calcined usingconventional techniques to form the final catalyst. This final catalystcontained 5.8% nickel, 12.8% MoO₃ and 4.75% by weight of phosphorus. Thesurface area of this product is 195 m²./gm. and it has a total porevolume of 0.88 cc./gm. This product has utility as a hydrocarbonhydrotreating catalyst.

EXAMPLE II

This example illustrates certain of the benefits of the presentinvention.

A final catalyst was prepared in the same manner as that of Example Iexcept that the phosphoric acid contacting occurred after the hydrousalumina was initially calcined and simultaneously with the impregnationwith nickel and molybdenum. This final catalyst contained 6.1% by weightof nickel, 13.0% by weight of MoO₃ and 6.3% by weight of phosphorus andhad a surface area of 79 m²./gm. and a total pore volume of 0.39 cc./gm.

EXAMPLE III

Example I is repeated except that an equivalent amount of P₂ O₅ is addedto the aqueous mixture in place of the H₃ PO₄. The final catalyst formedhas essentially the same chemical composition as that of Example I andhas a surface area in excess of 150 m²./gm. and a total pore volume inexcess of 0.60 cc./gm. This product has utility as a hydrocarbonhydrotreating catalyst.

EXAMPLE IV

Example I is repeated except that an equivalent amount ofphenylphosphonic acid is added to the aqueous mixture in place of thephosphoric acid and the mixture of water, hydrous alumina and acid inmulled at 130° F. for 15 minutes. The final catalyst formed whichincludes more than 0.5% by weight of phosphorous and has essentially thesame metals content as the final catalyst of Example I, as well assurface area in excess of 100 m²./gm. and a total pore volume in excessof 0.50 cc./gm., is found to have utility as a hydrocarbon hydrotreatingcatalyst.

EXAMPLE V

A calcined alumina is prepared as in Example I except that an equivalentamount of phosphorous acid is used in place of the phosphoric acid. Theparticles of calcined alumina are impregnated with catalyticallyeffective amounts of nickel and tungsten using conventional techniques.The resulting final catalyst, which contains more than 0.5% by weight ofphosphorous and has a surface area in excess of 100 m²./gm. and a totalpore volume in excess of 0.50 cc./gm., is found to have utility as ahydrocarbon hydrotreating catalyst.

That the final catalyst prepared as in Example I had a surface area anda total pore volume greater than that of the catalyst prepared inExample II is indicative of the fact that the catalyst preparedaccording to the present invention, e.g., Example I, has an improvedhydrocarbon hydrotreating activity relative to the final catalyst ofExample II. This improvement in hydrotreating activity is particularlysurprising since the final catalysts of Examples I and II have similarchemical compositions. Thus, the present catalyst preparation methoddoes provide catalysts with improved hydrocarbon hydrotreating activity.

In addition, Examples III to V illustrate that a wide variety ofphosphorus acids may be used in the present method. Also, various metalsand mixtures of metals in catalytically effective amounts may be used.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. In a method for producing an improved final catalyst comprising a major amount of alumina and a minor amount effective to promote hydrocarbon hydrotreating of at least one metal component selected from the group consisting of Group VIB metal components, Group VIII metal components and mixtures thereof which comprises the steps of contacting calcined alumina with at least one said metal-containing compound thereby forming a metal-containing material, calcining said metal-containing material and forming said final catalyst wherein the improvement which consists essentially of:(1) contacting an aqueous slurry consisting essentially of hydrous alumina with at least one phosphorus acid present in an amount sufficient to provide said final catalyst with a minor amount effective to increase the hydrocarbon hydrotreating activity of the final catalyst of phosphorus and forming a phosphorus-containing hydrous alumina, said phosphorus acid being selected from the group consisting of phosphoric acids, phosphonic acids, phosphinic acids, phosphenic acids, phosphoranic acids, phosphoranedioic acids, phosphoranetrioic acids, phosphoranetetroic acids, phosphoranepentoic acids and mixtures thereof, and (2) calcining said phosphorus-containing hydrous alumina and forming said calcined alumina.
 2. The method of claim 1 wherein said phosphorus acid is at least partially water soluble and is present in the aqueous slurry of step (1) in an amount such that at least about 0.01 mole of phosphorus per mole of alumina (calculated as Al₂ O₃) is present.
 3. The method of claim 2 wherein said hydrous alumina predominates in a material selected from the group consisting of alumina monohydrate, alumina trihydrate, amorphous hydrous alumina and mixtures thereof, and said phosphorus acid is present in the aqueous slurry of step (1) in an amount such that from about 0.01 mole to about 2.0 moles of phosphorus per mole of alumina (calculated as Al₂ O₃) is present.
 4. The method of claim 3 wherein said final catalyst contains at least about 0.5% by weight of phosphorus and from about 0.01% to about 2% by weight of Group VIII platinum-group metal (calculated as the free metal).
 5. The method of claim 4 wherein said final catalyst contains at least from 0.5% of phosphorus, from about 5% to about 40% by weight of said Group VIB metal component (calculated as the metal oxide) and from about 2% to about 15% by weight of Group VIII iron-group metal component (calculated as the free metal).
 6. The method of claim 5 wherein said hydrous alumina predominates in a material selected from the group consisting of alumina monohydrates, amorphous hydrous alumina and mixtures thereof, said phosphorus acid is selected from the group consisting of phosphoric acids, phosphorous acids and mixtures thereof, and said final catalyst contains from about 10% to about 30% by weight of said Group VIB metal component (calculated as the metal oxide) and from about 4% to about 10% by weight of said Group VIII iron group metal component (calculated as the free metal).
 7. The method of claim 6 wherein said phosphorus acid is selected from the group consisting of phosphoric acids and mixtures thereof, said Group VIB metal component is selected from the group consisting of tungsten component, molybdenum component, and mixtures thereof, and said Group VIII iron group metal component is selected from the group consisting of nickel component, cobalt component and mixtures thereof.
 8. The method of claim 7 wherein the calcination of steps (2) and (4) occur at a temperature in the range of about 600° F. to about 1200° F. for a period of time of at least about 1/2 hour. 